Seventh Sunday after Easter; commemorates the emanation of the Holy Spirit to the Apostles; a quarter day in Scotland WordNet 3.0 & Open English WordNet

Pentecost is a Christian holiday which takes place on the 50th day after Easter Sunday. Wikipedia

One of the prominent feasts in the Christian liturgical year. Wikipedia Disambiguation

Christian holiday commemorating the New Testament stories of the Holy Spirit descenting upon the Apostles of Jesus Wikidata

Feast on the fifthieth day after Passover which commemorates the descent of the Holy Spirit upon the Apostles. OmegaWiki

The particular (Jewish) Pentecost 49 days (inclusive) after the resurrection of Jesus on the (Jewish) Day of First Fruits, when (in Christian teaching) the Holy Spirit descended upon the Apostles with miraculous effects including the ability to explain the Gospel intelligibly in languages they did not know; or a similar occasion since. Wiktionary

The Sunday of the feast of Pentecost, seven weeks after Easter, when traditionally many Christians would be baptised, wearing white clothes. Wiktionary

The Sunday of the feast of Pentecost. Wiktionary (translation)